This invention relates to an improved Fischer-Tropsch process for the production of methane. More specifically, it relates to such a process which employs a supported ruthenium catalyst.
The art contains many examples of metals known to be useful in reacting carbon monoxide with hydrogen to produce a variety of compounds, including hydrocarbons and oxygenated compounds. These metals include, among others, Mo, W, Rh, Ru, Re, Pd, Ni, Co and Fe. In what has come to be called the Fischer-Tropsch Synthesis, carbon monoxide and hydrogen are reacted over a metal catalyst to produce saturated and unsaturated hydrocarbons and oxygenated compounds containing from 1 to as many as 1000 carbon atoms. The hydrocarbons can be aliphatic, alicyclic or aromatic. Commercial utilization of this synthesis prior to 1950 was accomplished largely in Germany and is summarized in Storch, Columbic and Anderson: The Fischer-Tropsch and Related Synthesis, John Wiley and Sons, New York 1951.
Ruthenium has been acknowledged to be the most active catalytic metal for the production of methane from H.sub.2 and CO. Catalysis Reviews, V.8, No.2, 159-210, at 181 (1973). Ruthenium catalysts having Group VB oxide supports are generally known. For example, U.S. Pat. No. 4,149,998 discloses a catalyst composition consisting of selected Group VIII metals supported on oxides of Group IVB or VB. Yet the majority of prior art Fischer-Tropsch processes and catalysts are not capable of selectively producing methane.
U.S. Pat. No. 4,171,320 discloses a catalyst comprising ruthenium on a crystalline support. The support is required to contain an oxide of a Group VB metal, e.g., tantalum. The catalysts are taught to be useful for the selective conversion of H.sub.2 and CO into olefins of from 2 to 5 carbon atoms.
Heretofore, a method for the high yield production of methane from H.sub.2 and CO using ruthenium supported on an oxide of a Group VB metal has not been disclosed.